1. Field of the Invention
The present invention relates to an information recording apparatus such as a computer including a Redundant Array of Independent Disks (RAID) configuration, which operates a plurality of recording apparatuses in parallel.
2. Description of the Related Art
In a computer system, a RAID technique has been used as a technique of allowing high-speed access to a recording apparatus such as a hard disk drive (HDD), and improving its reliability. RAID is a technique for increasing access speed and improving reliability by exploiting the redundancy of data in a plurality of HDDs. Various types of RAID configuration, e.g., RAID0, RAID1, and RAID5 are defined.
More specifically, RAID1, RAID5, and the like feature redundant of the data. Hence, if one HDD which forms part of a RAID configuration fails, the data stored in the failed HDD can be calculated and generated from the data in the remaining normal HDDs. Generally, when one HDD fails in this system, the failed HDD is replaced with a new one. The data are then sequentially read from the remaining normal HDDs to calculate and generate the data to be stored in the failed HDD. After that, the obtained data is written in sectors designated by all addresses of the new HDD (to be referred to as a “rebuild process” hereinafter). Accordingly, the data which has been stored in the failed HDD can be restored (e.g., see Jpn. Pat. Appln. KOKAI Publication No. 2004-38290).
As described above, RAID1, RAID5, and the like have redundant data, and consistency of these data must be kept. If the consistency cannot be kept, the above-described rebuild process cannot be performed normally. Hence, in a system such as a RAID1 or RAID5 system which has redundant data, consistency is generally checked periodically (to be referred to as a consistency check hereinafter).
RAID is widely used in a server or the like as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-038290. According to a recent proposal, RAID is applied to a device such as a notebook-type personal computer (PC) which is portable (to be referred to as a “portable device” hereinafter). In this portable device, the HDD may fail due to vibration while carrying the device. Hence, RAID can be applied to the portable device, thus increasing its reliability.
The above-described portable device can be generally driven by a battery. The above-described rebuild process and consistency check are time-consuming processes with high power consumption. Hence, when the above-described RAID is applied to such a portable device, power is consumed in the rebuild process and consistency check, and operation time can be shortened.
A computer disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2004-038290 incorporates a battery. However, this computer is presumed to mainly receive power from an external power supply but not from the battery.